Observational bounds on the quantity M × ν_U obtained for Galactic microquasars vs. relations predicted by the epicyclic resonance model. The vertical areas denote the observational bounds on M × ν_U determined for GRS 1915+105, XTE J1550−564, and GRO J1655−40. The areas are drawn assuming the conservative limits from Table 1. The solid black curve shows predictions of the model calculated for the geodesic flow. The shaded region indicates the interval predicted by the model for the family of equilibrium non-slender fluid tori of all thicknesses possible in the particular case. The red curve corresponds to the case of tori with a cusp. The arrow labelled Δ a indicates the shift of the lower limit on the spin of microquasars implied by considering the non-geodesic flow.